Field of the Invention
The present invention relates to a magnetic resonance measurement apparatus, and in particular to a transfer technique of an instruction sequence for executing a pulse sequence.
Description of Related Art
As magnetic resonance measurement apparatuses, nuclear magnetic resonance (NMR) measurement apparatuses and electron spin resonance (ESR) measurement apparatuses are known. In addition, as apparatuses classified as NMR measurement apparatuses, magnetic resonance imaging (MRI) apparatuses are also known. In the following, NMR measurement apparatuses will be described.
NMR refers to a phenomenon where an atomic nucleus under a static magnetic field interacts with an electromagnetic wave having a frequency intrinsic to the atomic nucleus. An apparatus that executes measurement of a sample at an atomic level taking advantage of this phenomenon is an NMR measurement apparatus. Currently, NMR measurement apparatuses are used in analyses of organic compounds (for example, medicines and agricultural chemicals), polymer materials (for example, vinyl and polyethylene), biological substances (for example, nucleic acids and proteins), and the like. With the use of an NMR measurement apparatus, for example, a molecular structure of the sample can be revealed.
An NMR measurement apparatus generally includes a control computer, a radio frequency (RF) signal transmitter, an NMR signal detector (probe), a static magnetic field generator (superconductive magnet), an NMR signal receiver, and the like. In some cases, a part of these structures is called an NMR measurement apparatus. For example, a part of a spectrometer including the control computer, the RF signal transmitter, and the NMR signal receiver may be called an NMR measurement apparatus. In a typical NMR measurement, a high-frequency signal for NMR measurement (RF transmission signal) is generated in the transmitter, and the transmission signal is supplied to a transmission and reception coil in the probe. A resonance absorption phenomenon is caused in an observation nucleus in the sample due to an electromagnetic wave caused by the transmission signal. An NMR signal induced in the transmission and reception coil (RF reception signal) is then transmitted to the receiver, and a spectrum of the received signal is analyzed.
In the NMR measurement apparatus, a pulse program is compiled by a compiler and a sequence of instructions (instruction sequence) is generated. The pulse program is a description of a pulse sequence for realizing a desired NMR measurement. The sequence of instructions is transferred from the compiler to a sequencer unit. The sequencer unit controls operations of the transmitter, the receiver, or the like of the NMR measurement apparatus according to the transferred instruction sequence. In this manner, the NMR measurement is realized.
As the NMR measurement becomes more complex, the quantity of instruction sequences given to the sequencer unit becomes large, and the transfer time of the instruction sequence is also increased. In addition, when the instruction sequence is to be transferred from the compiler to the sequencer unit using a general bus, there is a restriction on the transfer rate. Further, there is a restriction on storage areas of the transfer destination. Because of the restriction on the transfer range, if the pulse sequence operation is to be started after the entirety of the instruction sequence is generated and transferred to the sequencer unit, there is a problem in that the startup of the sequencer unit, and consequently, the start of the measurement, is delayed. In addition, in this configuration, it is necessary to secure a storage area of a large capacity at the transfer destination. In order to handle this, a configuration may be considered in which the measurement is started while the generation and the transfer of the instruction sequence are executed in parallel to each other. However, if there is a sequence of a high density portion in the instruction sequence (for example, an instruction portion for quickly changing many parameters in a short time), the generation and transfer of the instruction sequence would be delayed at that portion, and, as a result, a case may be caused in which the instruction sequence to be referred to by the sequencer unit is exhausted. Such a problem also arises in other magnetic resonance measurement apparatuses.
In an NMR apparatus disclosed in JP 2007-335958 A, a pulse sequence is divided into a plurality of kinds according to a characteristic of the pulse, and the data of unit pulse of each kind is stored in a corresponding segment memory. However, JP 2007-335958 A does not disclose a structure for handling the delay of the start of the measurement and exhaustion of the instruction sequence.
An advantage of the present invention is that, in a magnetic resonance measurement apparatus, delay of the start of the measurement is reduced or prevented, and exhaustion of the instruction sequence to be referred to by the sequencer unit is avoided.